Ceres, a dwarf planet with an orbit between Mars and Jupiter, might once be home to numerous cryovolcanoes that might have disappeared over millions of years, a new study suggested.

While volcanoes on Earth are fueled by molten rock, Ceres is too small and cold to melt silicate rock in its core. Yet scientists discovered the huge Ahuna Mons volcano of icy rock that they call a cryovolcano.

Now, the new study indicated that the dwarf plant had numerous cryovolcanoes other than Ahuna Mons but they gradually flattened out over time and become impossible to tell apart from the planet’s surface.

Lead researcher Michael Sori, from Tucson-based University of Arizona, said, “We think we have a very good case that there have been lots of cryovolcanoes on Ceres, but they have deformed.”

Ahuna Mons is one of the most prominent features on the dwarf planet, rising to more than half the height of Earth’s Mount Everest. Its lonely existence has been puzzling researchers since they spotted it.

The researchers concluded that either Ahuna Mons is a solitary feature formed recently, or cryovolcanoes are not unusual on the dwarf planet. There might be some process at play that has destroyed other cryovolcanoes. The new study appeared in the journal Geophysical Research Letters.